[Python-checkins] bpo-44608: Fix memory leak in _tkinter._flatten() (GH-27107)

[miss-islington]

https://github.com/python/cpython/commit/7e1d6308a3fc536719adcf1df0aa4e9953c12f8b
commit: 7e1d6308a3fc536719adcf1df0aa4e9953c12f8b
branch: 3.10
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: miss-islington <31488909+miss-islington at users.noreply.github.com>
date: 2021-07-13T22:40:10-07:00
summary:

bpo-44608: Fix memory leak in _tkinter._flatten() (GH-27107)


if it is called with a sequence or set, but not list or tuple.
(cherry picked from commit f572cbf1faab33d9afbbe3e95738ed6fbe6e48e6)

Co-authored-by: Serhiy Storchaka <storchaka at gmail.com>

files:
A Misc/NEWS.d/next/Library/2021-07-13-09-01-33.bpo-44608.R3IcM1.rst
M Lib/test/test_tcl.py
M Modules/_tkinter.c

diff --git a/Lib/test/test_tcl.py b/Lib/test/test_tcl.py
index e7a60db777820..6e5ef097c888f 100644
--- a/Lib/test/test_tcl.py
+++ b/Lib/test/test_tcl.py
@@ -43,8 +43,14 @@ def get_tk_patchlevel():
 class TkinterTest(unittest.TestCase):
 
     def testFlattenLen(self):
-        # flatten(<object with no length>)
+        # Object without length.
         self.assertRaises(TypeError, _tkinter._flatten, True)
+        # Object with length, but not sequence.
+        self.assertRaises(TypeError, _tkinter._flatten, {})
+        # Sequence or set, but not tuple or list.
+        # (issue44608: there were leaks in the following cases)
+        self.assertRaises(TypeError, _tkinter._flatten, 'string')
+        self.assertRaises(TypeError, _tkinter._flatten, {'set'})
 
 
 class TclTest(unittest.TestCase):
diff --git a/Misc/NEWS.d/next/Library/2021-07-13-09-01-33.bpo-44608.R3IcM1.rst b/Misc/NEWS.d/next/Library/2021-07-13-09-01-33.bpo-44608.R3IcM1.rst
new file mode 100644
index 0000000000000..e0cf948f3cba6
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-07-13-09-01-33.bpo-44608.R3IcM1.rst
@@ -0,0 +1,2 @@
+Fix memory leak in :func:`_tkinter._flatten` if it is called with a sequence
+or set, but not list or tuple.
diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 14101d9e3951c..329b291729d58 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -3197,8 +3197,10 @@ _tkinter__flatten(PyObject *module, PyObject *item)
 
     context.size = 0;
 
-    if (!_flatten1(&context, item,0))
+    if (!_flatten1(&context, item, 0)) {
+        Py_XDECREF(context.tuple);
         return NULL;
+    }
 
     if (_PyTuple_Resize(&context.tuple, context.size))
         return NULL;